Heating/ventilating/air conditioning systems for vehicles

ABSTRACT

An HVAC Integrated electronic Module (HIM) ( 41 ) for controlling airflow through an HVAC module ( 12 ), the HVAC module including a variable speed blower motor ( 18 ), a plurality of airflow doors ( 26 - 28 ) for controlling air direction and hot-cold air temperature blend, and electrical actuators, servo motors or stepper motors for said doors, the HIM including: one or more air temperature sensors ( 22 ) for measurement of one or more of intake air temperature, outlet air temperature, air-off evaporator temperature and engine coolant temperature; actuator control circuitry ( 31 ) for controlling said electrical actuators, servo motors or stepper motors; blower motor speed control circuitry ( 15 ) for speed control of the variable speed blower motor; sensor control circuitry for said sensors; and communication circuitry for a serial communication interface ( 42 ) to enable communication with a vehicle users interface ( 32 ).

[0001] This invention relates to improvements in heating/ventilation/airconditioning systems (HVAC) in vehicles, particularly motor vehicles,and relates particularly to an improved method of controlling theairflow and temperature through the HVAC module by integration of thecontrolling devices into a HVAC Integrated electronic Module (HIM)controlled by a serial communication bus.

[0002] Current technology in HVAC generally comprises a user interface(Climate Control) by which the driver or passenger controls the airflow,and a HVAC module which directs airflow from one or more inlet points,through heater cores and/or evaporator cores and onto a number ofoutlets. The Climate Control may comprise a dedicated user interface forcontrolling the HVAC system or it may be integrated into a CentralControl and display together with other vehicle functions. The airflowthrough the HVAC module is generally controlled by airflow doors toopen, close or blend the air through various passages through the HVACmodule. Airflow doors may comprise Butterfly doors, Clamshell doors orroller vanes.

[0003] The Climate Control may connect to the HVAC module either by anelectrical control system or by a mechanical linkage or a combination ofboth. Where the UVAC module is electrically controlled, electricalactuators, servo motors or stepper motors are used for movement of theHVAC module airflow doors. The airflow speed is generally controlled byvarying the voltage across an electrical motor with airflow impeller(blower motor) by the use of electrical resistors or by a semiconductor(speed control unit). The speed control unit is controlled, in turn, bythe Climate Control. In a typical HVAC module, one or more of theelectrical actuators, servo motors or stepper motors may be used tocontrol the cold to hot air temperature blend (air mix) while otherelectrical actuators, servo motors or stepper motors are used to controlthe outlet airflow directions (mode), while other electrical actuators,servo motors or stepper motors are used to control the inlet airflowdirection (intake). In a typical HVAC module there will be a variety ofair temperature sensors for such measurements as intake air temperature,outlet air temperature, air-off evaporator temperature and enginecoolant temperature. In a typical HVAC module there will also be avariety of other electrical devices such as pressure sensors, humiditysensors, air quality sensors, air filter sensors (both pressure orinfrared) and positional sensors.

[0004] While current technology is relatively sophisticated, it is stillnecessary to connect the HVAC module to the other vehicle systems andthe Climate Control generally by employing a wiring harness forconducting electrical signals from the Climate Control to the HVACmodule. Consequently, a large plurality of wires and associatedconnectors are required in wiring the Climate Control to the HVACmodule.

[0005] Further, with current systems, different wiring harnesses arerequired where different HVAC module functionality or features areoffered through a vehicle model range.

[0006] It is therefore desirable to provide an improved HVAC system thatobviates at least some of the disadvantages of the current HVAC systems.

[0007] It is also desirable to provide an improved HVAC system that willbe economical to manufacture, install, validate and service.

[0008] It is also desirable to provide an improved HVAC module thatprovides increased functionality and features.

[0009] It is also desirable to provide a HVAC module that can be adaptedfor a variety of functional needs.

[0010] It is also desirable to reduce the electrical wiring on andassociated with the HVAC module and system.

[0011] In accordance with one aspect of the invention there is providedan HVAC Integrated electronic Module (HIM) for controlling airflowthrough an HVAC module, the HVAC module including a variable speedblower motor, a plurality of airflow doors for controlling air directionand hot-cold air temperature blend, and electrical actuators, servomotors or stepper motors for said doors, the HIM including:

[0012] one or more air temperature sensors for measurement of one ormore of intake air temperature, outlet air temperature, air-offevaporator temperature and engine coolant temperature;

[0013] actuator control circuitry for controlling said electricalactuators, servo motors or stepper motors;

[0014] blower motor speed control circuitry for speed control of thevariable speed blower motor;

[0015] sensor control circuitry for said sensors; and

[0016] communication circuitry for a serial communication interface toenable communication with a vehicle users interface.

[0017] Preferably, the HIM also includes electrical devices for sensinghumidity, air quality, air filter condition (both pressure or infrared)and position, as well as control circuitry for said electrical devices.

[0018] By redesigning the HVAC module to incorporate at least asignificant portion of the control circuitry which would otherwise beincorporated in the vehicle user interface, or Climate Control, or eachindividual electrical device mounted to the HVAC module and bycommunicating using a serial communication bus, substantially reducedelectrical wiring is required from the Climate Control to the HVACmodule, and it is no longer necessary to have a separate HVAC modulesub-wiring harness assembly connecting the actuators, blower motor speedcontrol unit, air temperature sensors and various other electricaldevices to the Climate Control.

[0019] Further, because according to this invention, at least asignificant portion of the all control circuitry is now located in theIntegrated HVAC electronic Module (HIM), a greater degree of testing canoccur on the HVAC module prior to assembly in the vehicle and, once inthe vehicle, a greater degree of testing can occur to the HVAC systemprior to assembly of the instrument panel in the vehicle. Still further,with the integration of circuitry and mechanisms with the HIM a greaterdegree of functionality is possible such as blower speed compensationwith road speed, blower speed compensation with air modes or temperatureblend, blower speed compensation during changes of air modes to preventair bursts, intake air bleed compensation for optimising HVAC systemperformance, ram air compensation with vehicle speed, blower speedcompensation with battery voltage, compensation for non-linearity's ofhot-cold temperature air mix door position versus outlet temperature,and the like.

[0020] Further, the invention control circuitry may either beimplemented by application of a microprocessor based control system ordiscrete electronic components. In the case of a microprocessor basedcontrol system and with input of outside air temperature and sunloadmeasurements, either discretely or on serial communication bus, the HVACIntegrated electronic Module (HIM) may also incorporate climate controlcircuitry implementing an Automatic Climate Control (ACC) strategy.

[0021] Further, the HVAC Integrated electronic Module (HIM) may use ashared serial communication bus with other electronic modules in thevehicle to enable shared data between said electronic modules and theHIM and also enable the HIM to have diagnostic interrogation through asingle point vehicle diagnostic connection.

[0022] In order that the invention is more readily understood, anembodiment thereof will now be described with reference to theaccompanying drawings therein:

[0023]FIG. 1 is a diagrammatic view of an HVAC unit in accordance withone embodiment of the invention;

[0024]FIG. 2 is a schematic wiring diagram illustrating the wiringsystem of a prior art HVAC unit; and

[0025]FIG. 3 is a schematic wiring diagram illustration the wiringsystem for an HVAC unit in accordance with the present invention.

[0026] Referring to the drawings, an HVAC module comprises a mechanicalsystem, diagrammatically shown in FIG. 1, which incorporates a pluralityof doors to direct airflow from the intake to the outlets. The airintake 14 draws air from outside the vehicle cabin (fresh air) while airintake 16 draws airflow from within the vehicle cabin (recirculatedair). An air intake door 17 is movable by an electrical actuator, servomotor or stepper motor (not shown) to vary the blend of fresh andrecirculated air.

[0027] A blower motor 18 is used to push air through the HVAC module 12.The blower motor is controlled by a speed control unit 15 that usesairflow through the HVAC module to dissipate heat. An evaporator core 21is used to reduce the air temperature as air flows through its fins. Aheater core (not shown) is similarly used to increase air temperature asair flows through its fins. An air mix door is used to vary the blend ofhot air (that which has flowed through the heater core) with cold air(that which has flowed through the evaporator core 21) and is controlledin position by an electrical actuator, servo motor or stepper motor.Various mode doors are used to direct airflow to various outlets usuallycomprising screen 26, face 27 and foot 28 or any combination thereof.The electrical actuators, servo motors and stepper motors for moving thedoors are well known in the art and do not need to be described indetail.

[0028] Various temperature sensors, one of which is shown at 30, areused at various positions throughout the HVAC module to measure airtemperatures for particular climate control strategies. Variouselectrical devices (not shown) such as pressure sensors, humiditysensors, air quality sensors, air filter sensors (both pressure orinfrared) and positional sensors are also used at various locations onthe HVAC module for particular climate control strategies. The use oftemperature sensors, pressure sensors and other electrical devices isgenerally known in the art.

[0029] In accordance with the present invention, some or all of theseelectrical or electro-mechanical devices are integrated into a singleHVAC Integrated electronic Module (HIM). The HVAC. Integrated electronicModule (HIM) incorporates electronic control circuitry 31 for thevarious electrical actuators, servo motors or stepper motors, thevarious temperature sensors, the blower motor speed control unit and thevarious electrical devices such as pressure sensors, humidity sensors,air quality sensors, air filter sensors (both pressure or infrared) andpositional sensors.

[0030] As shown in FIG. 2, in prior art HVAC module, the control of thevarious functions are effected from the vehicle user interface orClimate Control 32. The Climate Control 32 then controls the variouselectrical actuators, servo motors or stepper motors on the HVAC module40 by means of a plurality of individual electrical wires 36 eachrelated to a particular function, operational mode or airflow speed.Thus, the prior art HVAC module 40 illustrated has an air-offtemperature sensor 22, an air mix motor 34, mode outlet motor 33,recirculate motor 35 and blower motor 19 each connected by a pluralityof wires 36 to the Climate Control 32 for power supply and functionalcontrol. These electrical wires 36 include five (5) high current wiresfor the blower motor 19. A wiring harness and associated connectors fortwenty two (22) separate wiring connections is therefore required forthe HVAC module 12 to connect the module to the Climate Control 32 andthe vehicle wiring system 37.

[0031] As shown in FIG. 3, in accordance with the present invention, theintegration of the control circuitry 31 into the HVAC Integratedelectronic Module (HIM) 41, and the use of a serial communication bus,reduces the number of control electrical wires 36. In the embodimentillustrated in FIG. 3, with the same components as in the prior artmodule, only five (5) wires are required for power and communicationwith the Climate Control 32, and only two (2) of these are high currentwires. The HVAC serial bus signals:

[0032] A/C Switch

[0033] A/C Request

[0034] A/C Thermister

[0035] Blower speed

[0036] Recirculate control

[0037] Air direction control

[0038] Temperature control

[0039] With the system of the present invention, internal faultdetection may also be achieved as a feature of the control circuitry 31.A diagnostic connector 38 may plug into the serial communication bus toenable testing and diagnostic equipment to interrogate the HIM 41 modulein the event of faults or re-programming requirements. In accordancewith the present invention various additional functional features can beapplied to the control circuitry 31 without the need to make changes tothe wiring harnesses, vehicle electrical hardware or mechanicalhardware. For example, the number of operational modes may be increasedor decreased or varied to provide more, less or different positions ofair control doors without the need to change wiring.

[0040] Many other modifications may be made in the design and orconstruction of an HVAC Integrated electronic Module (HIM) in accordancewith the present invention and all such modifications which come withinthe scope of the invention shall be deemed to be within the ambit of theabove description.

1. An HVAC Integrated electronic Module (HIM) for controlling airflowthrough an HVAC module, the HVAC module including a variable speedblower motor, a plurality of airflow doors for controlling air directionand hot-cold air temperature blend, and electrical actuators, servomotors or stepper motors for said doors, the HIM including: one or moreair temperature sensors for measurement of one or more of intake airtemperature, outlet air temperature, air-off evaporator temperature andengine coolant temperature; actuator control circuitry for controllingsaid electrical actuators, servo motors or stepper motors; blower motorspeed control circuitry for speed control of the variable speed blowermotor; sensor control circuitry for said sensors; and communicationcircuitry for a serial communication interface to enable communicationwith a vehicle users interface.
 2. An HIM according to claim 1, andfurther including: one or more electrical devices for sensing one ormore of pressure, humidity, air quality, air filter condition andposition; and electrical device control circuitry for said electricalsensing devices.
 3. An HIM according to claim 2, wherein said one ormore electrical devices for sensing air filter condition use either orboth of infra-red or pressure sensing.
 4. An HIM according to any one ofthe preceding claims, wherein the control circuitry is implemented byapplication of a microprocessor based control system.
 5. An HIMaccording to claim 4, and further including climate control circuitryimplementing an Automatic Climate Control (ACC) strategy based uponmeasurement of outside air temperature and sun-load measurements, eitherdiscretely or on said serial communication bus.
 6. An HIM according toany one of claims 1 to 4, wherein the control circuitry is implementedby application of discrete electronic components.
 7. An HIM according toany one of the preceding claims, wherein the serial communication bus isadapted to be shared with other electronic modules in the vehicle toenable data to be shared between said other electronic modules and theHIM and also enable diagnostic interrogation to be performed on the HIMthrough a single point vehicle diagnostic connection.